Oily cold water fish, such as salmon, trout, herring, and tuna are the source of dietary marine omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) being the key marine derived omega-3 fatty acids. Both niacin and marine omega-3 fatty acids (EPA and DHA) have been shown to reduce cardiovascular disease, coronary heart disease, atherosclerosis and reduce mortality in patients with dyslipidemia, hypercholesterolemia, or Type 2 diabetes, and metabolic disease. Niacin at high dose (1.5 to 4 grams per day) has been shown to improve very low-density lipoprotein (“VLDL”) levels through lowering Apolipoprotein B (“ApoB”) and raising high density lipoprotein (“HDL”) through increasing Apolipoprotein A1 (“ApoA1”) in the liver. Niacin can also inhibit diacylglycerol acyltransferase-2, a key enzyme for TG synthesis (Kamanna, V. S.; Kashyap, M. L. Am. J. Cardiol. 2008, 101 (8A), 20B-26B). Unfortunately, niacin has many actions outside of the liver that detract from its therapeutic utility. The most common side effect of niacin is flushing, which can limit the dose a patient can tolerate. Flushing is thought to occur through the GPR109 receptor in the vasculature. Non-flushing niacin derivatives have been disclosed in WO 2008/016968, and these derivatives are reported to potentially have the same beneficial effect on raising HDL as niacin while displaying a lesser degree of flushing.
Omega-3 fatty acids (such as DHA and EPA) have been shown to improve insulin sensitivity and glucose tolerance in normoglycemic men and in obese individuals. Omega-3 fatty acids have also been shown to improve insulin resistance in obese and non-obese patients with an inflammatory phenotype. Lipid, glucose, and insulin metabolism have been show to be improved in overweight hypertensive subjects through treatment with omega-3 fatty acids. Omega-3 fatty acids (EPA/DHA) have also been shown to decrease triglycerides and to reduce the risk for sudden death caused by cardiac arrhythmias in addition to improve mortality in patients at risk of a cardiovascular event. Omega-3 fatty acids have also been taken as part of the dietary supplement portion of therapy used to treat dyslipidemia.
Both DHA and EPA are characterized as long chain fatty acids (aliphatic portion between 12-22 carbons). Medium chain fatty acids are characterized as those having the aliphatic portion between 6-12 carbons. Lipoic acid is a medium chain fatty acid found naturally in the body. It plays many important roles such as free radical scavenger, chelator to heavy metals and signal transduction mediator in various inflammatory and metabolic pathways, including the NF-κB pathway (Shay, K. P. et al. Biochim. Biophys. Acta 2009, 1790, 1149-1160). Lipoic acid has been found to be useful in a number of chronic diseases that are associated with oxidative stress (for a review see Smith, A. R. et al Curr. Med. Chem. 2004, 11, p. 1135-46). Lipoic acid has now been evaluated in the clinic for the treatment of diabetes (Morcos, M. et al Diabetes Res. Clin. Pract. 2001, 52, p. 175-183) and diabetic neuropathy (Mijnhout, G. S. et al Neth. J. Med. 2010, 110, p. 158-162). Lipoic acid has also been found to be potentially useful in treating cardiovascular diseases (Ghibu, S. et al, J. Cardiovasc. Pharmacol. 2009, 54, p. 391-8), Alzheimer's disease (Maczurek, A. et al, Adv. Drug Deliv. Rev. 2008, 60, p. 1463-70) and multiple sclerosis (Yadav, V. Multiple Sclerosis 2005, 11, p. 159-65; Salinthone, S. et al, Endocr. Metab. Immune Disord. Drug Targets 2008, 8, p. 132-42). Lipoic acid can potentially be useful in treating or preventing hypertriglyceridemia and diabetic dyslipidemia. Recent data suggested that the triglyceride-lowering effect of lipoic acid is due in part to its ability to stimulate triglyceride clearance and down-regulate liver triglyceride secretion, most likely via inhibition of DGAT-2 (Moreau et al, Archives of Biochemistry and Biophysics 2009, 485, p. 63-71).
The ability to provide the effects of non-flushing niacin and omega-3 fatty acid in a synergistic way would provide a great benefit in treating the aforementioned diseases.